Minerals in soil are washed away by groundwater and streams due to eluviation or the like by meteorological phenomena such as snow and rain. In addition, soil minerals are running out due to continuous cultivation of crops in limited sites and thus the yield of crops and the amount of nutrients in crops gradually decrease as time elapses.
Among the soil minerals, small amounts of trace elements are needed by plants. However, when balance among the trace mineral elements is broken or any one thereof is deficient in a considerable amount, crops suffer physiological disorders. The physiological disorders are not easily remedied and, consequently, massive economic losses occur due to inhibition of plant growth.
To address these problems, artificial supplements are applied to mineral deficient soils. Such supplements are referred to as fertilizers.
Thanks to recent development of chemical fertilizers, chemical fertilizers are generally used on croplands, such as rice fields, dry fields, green houses, and the like. When a chemical fertilizer is used, crop yield increases, whereas soil acidification is caused and, if used for extended periods of time, soil fertility is deteriorated.
To address these problems of chemical fertilizers, use of organic fertilizers is recommended. When the organic fertilizer is used, however, a production process thereof is complicated and it is labor consuming. Thus, general farmhouses mainly use organic composts that are commercially available.
Organic compost manufacturers are mainly manufacturing and selling non-fermented compost using sawdust. When non-fermented compost is used, however, odors are caused by gas, such as ammonia gas or the like, generated after the non-fermented compost is applied, and crops cannot be grown. Thus, farmhouses are unwilling to use commercially available organic composts.
In addition, these days, an organic fertilizer manufactured by mixing used briquettes, sawdust and the like with livestock wastes and fermenting the mixture is commercially available. When the organic fertilizer using livestock wastes is used, however, odors occur when spraying the organic fertilizer and supply of minerals is still deficient in spite of supply of a large amount of organic substances, and thus, it is impossible to efficiently absorb various ingredients needed for growth of plants.
Meanwhile, plants absorb various elements based on the least abundant element among all absorbable elements according to Liebig's Law of the Minimum. In this regard, in a case in which mineral ingredients, which are trace elements, are deficient, even though a large amount of an organic fertilizer containing nitrogen, phosphorus, potassium, and the like is supplied, it only accelerates soil acidification and various necessary ingredients for growth may not be efficiently absorbed. Therefore, to grow plants, it is necessary to continuously supply mineral ingredients as well as organic ingredients.
Currently, research on fertilizers that may effectively supply these mineral ingredients is intensively conducted in the field of agriculture and gardening. In addition, single salts such as silicates and the like are mainly used as the mineral ingredients supplied to plants, and are generally used in an aqueous solution state.
When various mixed minerals needed for plants are prepared by mixing these single salts, however, preparation thereof is difficult due to reactions such as agglomeration, precipitation, or the like. In addition, when mineral ingredients are prepared by mixing chemically prepared single salts, it is very difficult to prepare a fertilizer containing various mineral ingredients needed for plants. Furthermore, when chemically prepared mineral ingredients are accumulated in soil, the single ingredients are concentrated therein and thus may adversely affect plants.